SMTP server outlook mail causes basic issues with send/receive due to the security restrictions and some file folder corruptions. The basic troubleshooting includes checking the configuration settings and then test the protocols using test emails. The SMTP is a basic entity that corrupts quickly when there are changes on the Internet services. If you change the Internet service providers, issues may arouse with sending and receiving emails. Outlook program stops sending emails when port 25 is blocked by the firewall.
It is required to manually open the blocked ports to resume the services for outbound emails. It can be found under system management utility.
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